C. Krause, B. Uysal, M. Engler, C. Radek, M. Schaudig
Abstract Ensuring product and part quality impacts manufacturing productivity, efficiency and profitability. The goal of every manufacturing company is to quickly identify reduced quality in order to take appropriate measures to improve quality. The use of non-destructive testing methods such as Barkhausen noise in combination with artificial intelligence (AI), which immediately classifies the data, offers a way to implement the desired quality monitoring in a production line. In the present study, the measured data of the Barkhausen signal of surface hardened components with different degrees of tempering were analyzed. For this purpose, suitable AI models were developed and trained with the processed measurement data to generate prediction values for the surface hardness. Data preparation and further processing was carried out using the Spyder development environment with the Python programming language. The following models were applied, tested and optimized during the study: Support vector machine, random forest regression and an artificial neural network. The models were able to predict hardness levels with high accuracy after effective training. Overall, the neural network showed the best results. The applied procedures and methods are fast, non-destructive and provide results with acceptable measurement error, which allows their use in the production environment. Further improvements will be sought in the future, e. g. by applying a larger amount of training data, by changing the features used in the training and by increasing the measurement accuracy when capturing the Barkhausen signal.
{"title":"Application of Machine Learning Techniques to Determine Surface Hardness Based on the Barkhausen Effect","authors":"C. Krause, B. Uysal, M. Engler, C. Radek, M. Schaudig","doi":"10.1515/htm-2022-1029","DOIUrl":"https://doi.org/10.1515/htm-2022-1029","url":null,"abstract":"Abstract Ensuring product and part quality impacts manufacturing productivity, efficiency and profitability. The goal of every manufacturing company is to quickly identify reduced quality in order to take appropriate measures to improve quality. The use of non-destructive testing methods such as Barkhausen noise in combination with artificial intelligence (AI), which immediately classifies the data, offers a way to implement the desired quality monitoring in a production line. In the present study, the measured data of the Barkhausen signal of surface hardened components with different degrees of tempering were analyzed. For this purpose, suitable AI models were developed and trained with the processed measurement data to generate prediction values for the surface hardness. Data preparation and further processing was carried out using the Spyder development environment with the Python programming language. The following models were applied, tested and optimized during the study: Support vector machine, random forest regression and an artificial neural network. The models were able to predict hardness levels with high accuracy after effective training. Overall, the neural network showed the best results. The applied procedures and methods are fast, non-destructive and provide results with acceptable measurement error, which allows their use in the production environment. Further improvements will be sought in the future, e. g. by applying a larger amount of training data, by changing the features used in the training and by increasing the measurement accuracy when capturing the Barkhausen signal.","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82117269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Strauss, P. Quadbeck, O. Andersen, S. Riecker, H. Böhm, T. Weissgärber
Abstract Binder-based additive manufacturing processes for metallic AM components in a wide range of applications usually use organic binders and process-related additives that must be thermally removed before sintering. Debinding processes are typically parameterized empirically and thus far from the optimum. Since debinding based on thermal decomposition processes of organic components and the subsequent thermochemical reactions between process atmosphere and metal powder materials make uncomplicated parameterization difficult, in-situ instrumentation was introduced at Fraunhofer IFAM. This measurement method relies on infrared spectroscopy and mass spectrometry in various furnace concepts to understand the gas processes of decomposition of organic components and the subsequent thermochemical reactions between the carrier gas atmosphere and the metal part, as well as their kinetics. This method enables an efficient optimization of the temperature-time profiles and the required atmosphere composition to realize dense AM components with low contamination. In the paper, the optimization strategy is presented, and the achievable properties are illustrated using a fused filament fabrication (FFF) component example made of 316L stainless steel.
{"title":"Gas Analysis and Optimization of Debinding and Sintering Processes for Metallic Binder-Based AM*","authors":"A. Strauss, P. Quadbeck, O. Andersen, S. Riecker, H. Böhm, T. Weissgärber","doi":"10.1515/htm-2022-1033","DOIUrl":"https://doi.org/10.1515/htm-2022-1033","url":null,"abstract":"Abstract Binder-based additive manufacturing processes for metallic AM components in a wide range of applications usually use organic binders and process-related additives that must be thermally removed before sintering. Debinding processes are typically parameterized empirically and thus far from the optimum. Since debinding based on thermal decomposition processes of organic components and the subsequent thermochemical reactions between process atmosphere and metal powder materials make uncomplicated parameterization difficult, in-situ instrumentation was introduced at Fraunhofer IFAM. This measurement method relies on infrared spectroscopy and mass spectrometry in various furnace concepts to understand the gas processes of decomposition of organic components and the subsequent thermochemical reactions between the carrier gas atmosphere and the metal part, as well as their kinetics. This method enables an efficient optimization of the temperature-time profiles and the required atmosphere composition to realize dense AM components with low contamination. In the paper, the optimization strategy is presented, and the achievable properties are illustrated using a fused filament fabrication (FFF) component example made of 316L stainless steel.","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87886498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Böcker, A. Puth, A. Pipa, J. H. Helden, J. Röpcke, H. Biermann, A. Dalke
Abstract Plasma nitrocarburizing by means of active screen technology using an active screen made of carbon fiber-reinforced carbon was carried out by varying the power at the active screen and using oxygen-containing fresh gas components (O2, CO2) in the N2:H2 plasma using the example of the quenched and tempered steel AISI 4140 (42CrMo4). The investigations focused on the analysis of the process gas by means of laser absorption spectroscopy, the evaluation of the produced compound layers with regard to structure and phase composition, as well as the resulting properties. It was shown that by varying the process gas atmosphere, the structural composition of the compound layer and the concentration profiles of nitrogen and carbon can be specifically influenced. The high concentrations of carbon-containing compounds in the process gas resulted in complete suppression of γ’-Fe4N formation, but cementite was detected in the lower part of the compound layer. The addition of oxygen-containing fresh gases and the resulting change in process gas composition suppressed cementite formation. The results suggest that, in particular, high powers at the carbon active screen and the simultaneous addition of oxygen-containing gases results in the generation of nitrogen-rich, single-phase ε-compound layers.
{"title":"Influence of Plasma Power and Oxygen-Containing Process Gases in Active Screen Plasma Nitrocarburizing with Carbon Solid Source*","authors":"J. Böcker, A. Puth, A. Pipa, J. H. Helden, J. Röpcke, H. Biermann, A. Dalke","doi":"10.1515/htm-2022-1026","DOIUrl":"https://doi.org/10.1515/htm-2022-1026","url":null,"abstract":"Abstract Plasma nitrocarburizing by means of active screen technology using an active screen made of carbon fiber-reinforced carbon was carried out by varying the power at the active screen and using oxygen-containing fresh gas components (O2, CO2) in the N2:H2 plasma using the example of the quenched and tempered steel AISI 4140 (42CrMo4). The investigations focused on the analysis of the process gas by means of laser absorption spectroscopy, the evaluation of the produced compound layers with regard to structure and phase composition, as well as the resulting properties. It was shown that by varying the process gas atmosphere, the structural composition of the compound layer and the concentration profiles of nitrogen and carbon can be specifically influenced. The high concentrations of carbon-containing compounds in the process gas resulted in complete suppression of γ’-Fe4N formation, but cementite was detected in the lower part of the compound layer. The addition of oxygen-containing fresh gases and the resulting change in process gas composition suppressed cementite formation. The results suggest that, in particular, high powers at the carbon active screen and the simultaneous addition of oxygen-containing gases results in the generation of nitrogen-rich, single-phase ε-compound layers.","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80289495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"AWT-Info / HTM 05-2022","authors":"","doi":"10.1515/htm-2022-8015","DOIUrl":"https://doi.org/10.1515/htm-2022-8015","url":null,"abstract":"","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80125306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Mikulewitsch, J. Dong, D. Stöbener, J. Épp, A. Fischer
Abstract In nitriding furnaces, the nitriding result is currently only controlled indirectly via the nitriding potential based on gas sensors. Detrimental properties such as soft spots, insufficient compound layer thickness or strongly porous zones, which might result from reduced surface reactivity, are thus only detected post-process. Therefore, in-process measurements of the layer formation promise a real benefit for energy efficiency and process quality enhancement. Photothermal radiometry is a promising contactless method for layer inspection that so far showed qualitative correlations of the photothermal phase signal with material parameters and layer thicknesses. In this article, thickness and thermal conductivity of the compound layer are quantitatively determined by using a physical signal model for a least-squares approximation of in-process measured photothermal phase signals. In addition, the influence of roughness and surface curvature is investigated, with the model-based photothermal layer thickness measurement showing robustness to different surface conditions and allowing quantification of the layer thickness with uncertainties < 1 μm even during in-process measurement inside an industrial nitriding furnace.
{"title":"Influences on Quantitative Nitriding Layer Thickness Measurements using Model-Based Photothermal Radiometry","authors":"M. Mikulewitsch, J. Dong, D. Stöbener, J. Épp, A. Fischer","doi":"10.1515/htm-2022-1024","DOIUrl":"https://doi.org/10.1515/htm-2022-1024","url":null,"abstract":"Abstract In nitriding furnaces, the nitriding result is currently only controlled indirectly via the nitriding potential based on gas sensors. Detrimental properties such as soft spots, insufficient compound layer thickness or strongly porous zones, which might result from reduced surface reactivity, are thus only detected post-process. Therefore, in-process measurements of the layer formation promise a real benefit for energy efficiency and process quality enhancement. Photothermal radiometry is a promising contactless method for layer inspection that so far showed qualitative correlations of the photothermal phase signal with material parameters and layer thicknesses. In this article, thickness and thermal conductivity of the compound layer are quantitatively determined by using a physical signal model for a least-squares approximation of in-process measured photothermal phase signals. In addition, the influence of roughness and surface curvature is investigated, with the model-based photothermal layer thickness measurement showing robustness to different surface conditions and allowing quantification of the layer thickness with uncertainties < 1 μm even during in-process measurement inside an industrial nitriding furnace.","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73792298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Mahdavi, Ö. Kücükyildiz, K. Dahl, M. Somers, K. Poulios, T. Christiansen, M. Villa
Abstract Stainless steels containing both C and N have unique characteristics while requiring unconventional manufacturing methods. This latter feature also translates into a lack of systematic investigations into their properties. In this work, a series of 13 wt%Cr steels with various interstitial solid solutions of C and N was synthesized by high temperature solution nitriding, HTSN, of commercial 13 wt%Cr martensitic steels. Light optical microscopy was applied to reveal the microstructural features, which consisted of a combination of martensite and austenite in various ratios depending on the C and N content. The mechanical response was characterized by nanoindentation. Data analysis assumed a fixed hardening exponent and provided an estimate of the yield strength and Young’s modulus of the synthesized steels and their microstructural components. The comparison with literature data indicated that this estimate is sound for martensite, while the data for austenite suggests an underestimation of the hardening exponent for this phase. The investigation demonstrates the potential of HTSN for the synthesis of novel 13 wt%Cr steels alloyed with both C and N. Moreover, it suggests that the use of nanoindentation for extracting the mechanical properties is limited by the non-uniqueness of the method with regard to the hardening exponent.
{"title":"Rapid Screening of the Mechanical Properties of 13 wt%Cr Steels with Uncharted Combinations of C and N Contents","authors":"H. Mahdavi, Ö. Kücükyildiz, K. Dahl, M. Somers, K. Poulios, T. Christiansen, M. Villa","doi":"10.1515/htm-2022-1020","DOIUrl":"https://doi.org/10.1515/htm-2022-1020","url":null,"abstract":"Abstract Stainless steels containing both C and N have unique characteristics while requiring unconventional manufacturing methods. This latter feature also translates into a lack of systematic investigations into their properties. In this work, a series of 13 wt%Cr steels with various interstitial solid solutions of C and N was synthesized by high temperature solution nitriding, HTSN, of commercial 13 wt%Cr martensitic steels. Light optical microscopy was applied to reveal the microstructural features, which consisted of a combination of martensite and austenite in various ratios depending on the C and N content. The mechanical response was characterized by nanoindentation. Data analysis assumed a fixed hardening exponent and provided an estimate of the yield strength and Young’s modulus of the synthesized steels and their microstructural components. The comparison with literature data indicated that this estimate is sound for martensite, while the data for austenite suggests an underestimation of the hardening exponent for this phase. The investigation demonstrates the potential of HTSN for the synthesis of novel 13 wt%Cr steels alloyed with both C and N. Moreover, it suggests that the use of nanoindentation for extracting the mechanical properties is limited by the non-uniqueness of the method with regard to the hardening exponent.","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90213755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Schöning, M. Kadanik, M. Reich, S. Petersen, O. Kessler
Abstract Induction hardening of large bearing rings is a very challenging procedure due to the complex physical processes and their interactions, which need to be properly controlled to produce components meeting the imposed requirements of e.g. wind turbines. The different process parameters significantly alter the resulting microstructures and properties of such a bearing ring. The evolution of numerical simulations in the last decades allows the modelling of processes with a growing complexity. In this work, the challenges of a simulation model for induction surface hardening are shown and discussed. Besides the theoretical background of the interacting physical fields and a brief note about available software packages, the paper focusses on the elaboration of a necessary material database and on the specific problems of induction scan hardening processes for large bearing rings.
{"title":"Challenges of Numerical Simulation Models for Induction Surface Hardening of Large Bearing Rings","authors":"H. Schöning, M. Kadanik, M. Reich, S. Petersen, O. Kessler","doi":"10.1515/htm-2022-1013","DOIUrl":"https://doi.org/10.1515/htm-2022-1013","url":null,"abstract":"Abstract Induction hardening of large bearing rings is a very challenging procedure due to the complex physical processes and their interactions, which need to be properly controlled to produce components meeting the imposed requirements of e.g. wind turbines. The different process parameters significantly alter the resulting microstructures and properties of such a bearing ring. The evolution of numerical simulations in the last decades allows the modelling of processes with a growing complexity. In this work, the challenges of a simulation model for induction surface hardening are shown and discussed. Besides the theoretical background of the interacting physical fields and a brief note about available software packages, the paper focusses on the elaboration of a necessary material database and on the specific problems of induction scan hardening processes for large bearing rings.","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83301781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In a previous publication, the influence of various process steps during the case-hardening process on the resulting material properties of two distinct batches of ultra-clean gear steels were investigated. The steel batches were case-hardened in the as-delivered condition. However, in the industrial practice it is common that pre-heat treatments are done, such as annealing to a ferritic-pearlitic microstructure, or quenching and tempering, as well as forging as a process if for example larger gears are needed. It is known that the whole heat treatment process route can affect the grain size negatively. Therefore, this publication presents investigations into the effects of preheat treatments on the grain size in the core region of ultra-clean gear steels after case-hardening. The aim is to receive a deeper understanding on how the whole process route influences the grain size in the core region of ultra-clean gear steels.
{"title":"Influence of Different Pre-Heat Treatments on the Grain Size in the Core Region of Ultra-Clean Gear Steels","authors":"S. Rommel, D. Fuchs, T. Blum, T. Tobie, K. Stahl","doi":"10.1515/htm-2022-1016","DOIUrl":"https://doi.org/10.1515/htm-2022-1016","url":null,"abstract":"Abstract In a previous publication, the influence of various process steps during the case-hardening process on the resulting material properties of two distinct batches of ultra-clean gear steels were investigated. The steel batches were case-hardened in the as-delivered condition. However, in the industrial practice it is common that pre-heat treatments are done, such as annealing to a ferritic-pearlitic microstructure, or quenching and tempering, as well as forging as a process if for example larger gears are needed. It is known that the whole heat treatment process route can affect the grain size negatively. Therefore, this publication presents investigations into the effects of preheat treatments on the grain size in the core region of ultra-clean gear steels after case-hardening. The aim is to receive a deeper understanding on how the whole process route influences the grain size in the core region of ultra-clean gear steels.","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90886985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The impact of plasma nitriding on the microstructure and the hardness of a recently developed 4 wt.-% medium manganese steel are presented. In contrast to standard quench and tempering steels, the investigated material achieves its martensitic microstructure by air-cooling from the forging heat, which enables the reduction of the carbon footprint of the forged components. The influence of nitriding on this grade of steel has not been investigated so far, but fundamental differences in comparison to standard nitriding steels are expected due to the increased manganese concentration. To address this issue, nitriding treatments with different temperatures (350 °C, 580 °C and 650 °C) have been performed, followed by examinations of the microstructure, the phase composition, the obtained hardness profiles and the tensile properties of the bulk material after nitriding, accompanied by thermodynamic equilibrium calculations. It is demonstrated that after nitriding at 580 °C similar hardness profiles like standard nitriding steels are achieved, with a shorter process as austenitization and hardening were omitted, reaching a hardness of approximately 950 HV0.1. Furthermore, it was demonstrated that austenite can be stabilized by manganese and nitrogen partitioning to room temperature during nitriding in the intercritical phase region.
{"title":"Plasma Nitriding of an Air-Hardening Medium Manganese Forging Steel","authors":"A. Gramlich, M. Auger, S. Richter","doi":"10.1515/htm-2022-1017","DOIUrl":"https://doi.org/10.1515/htm-2022-1017","url":null,"abstract":"Abstract The impact of plasma nitriding on the microstructure and the hardness of a recently developed 4 wt.-% medium manganese steel are presented. In contrast to standard quench and tempering steels, the investigated material achieves its martensitic microstructure by air-cooling from the forging heat, which enables the reduction of the carbon footprint of the forged components. The influence of nitriding on this grade of steel has not been investigated so far, but fundamental differences in comparison to standard nitriding steels are expected due to the increased manganese concentration. To address this issue, nitriding treatments with different temperatures (350 °C, 580 °C and 650 °C) have been performed, followed by examinations of the microstructure, the phase composition, the obtained hardness profiles and the tensile properties of the bulk material after nitriding, accompanied by thermodynamic equilibrium calculations. It is demonstrated that after nitriding at 580 °C similar hardness profiles like standard nitriding steels are achieved, with a shorter process as austenitization and hardening were omitted, reaching a hardness of approximately 950 HV0.1. Furthermore, it was demonstrated that austenite can be stabilized by manganese and nitrogen partitioning to room temperature during nitriding in the intercritical phase region.","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75562575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract While maraging steels are excellent candidates for additive manufacturing of high-strength materials, most of them provide little to no corrosion resistance. In this study, the surface of additively manufactured maraging steel is augmented with diffusion-based chromizing. The diffusion of chromium into the surface results in the formation of α-Cr, σ-phase and austenite depending on the chromium content at the respective distance from the surface. The bulk consists of a ductile bcc martensite hardened by precipitation of intermetallics during a low temperature ageing treatment. The σ-case provides a very high hardness, while the austenite phase is rather soft and unaffected by the ageing treatment. The chromizing treatment significantly reduced the corrosion rate of the maraging steel up to a factor of 14. Decomposition of the σ-case into a uniform case of austenite (austenitic stainless steel) further improved the corrosion resistance almost 24 times. This showed the strong potential of the chromizing treatment on a highstrength material to obtain a combination of their beneficial properties.
{"title":"Chromizing of Additively Manufactured Maraging Steel; Microstructural Evolution and Corrosion Performance","authors":"C. V. Funch, K. Dahl, T. Christiansen, M. Somers","doi":"10.1515/htm-2022-1012","DOIUrl":"https://doi.org/10.1515/htm-2022-1012","url":null,"abstract":"Abstract While maraging steels are excellent candidates for additive manufacturing of high-strength materials, most of them provide little to no corrosion resistance. In this study, the surface of additively manufactured maraging steel is augmented with diffusion-based chromizing. The diffusion of chromium into the surface results in the formation of α-Cr, σ-phase and austenite depending on the chromium content at the respective distance from the surface. The bulk consists of a ductile bcc martensite hardened by precipitation of intermetallics during a low temperature ageing treatment. The σ-case provides a very high hardness, while the austenite phase is rather soft and unaffected by the ageing treatment. The chromizing treatment significantly reduced the corrosion rate of the maraging steel up to a factor of 14. Decomposition of the σ-case into a uniform case of austenite (austenitic stainless steel) further improved the corrosion resistance almost 24 times. This showed the strong potential of the chromizing treatment on a highstrength material to obtain a combination of their beneficial properties.","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82913551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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